Variable power transmission mechanism



Aug. 4, 1942.

P. B. S TREICHET AL 2,291,928

VARIABLE POWER TRANSMISSION MECHANISM 3 Sheets-Sheet 1 ...unllll 4, P.B. STREICH ETAL 2,2

VAHIABLE POWER TRANSMISSION MECHANISM Filed Jan. 18, 1941" 5Sheets-Sheet 2 Aug. 1942- P. B. STREIICH ETAL. 2, 1,

VARIABLE POWER TRANSMISSION MECHANISM Filed Jan. 18, 1941 5 Sheets-Sheet3 Patented Aug. 4, 1942 VARIABLE rowan TRANSMISSION MEC HANISM Paul B.Streich, Maywood, and Herbert G. Macdonald, Oak Park, Ill., assignors toCharles Bruning 00., 'Inc., Chicago, 11]., a corporation of IllinoisApplication January 18, 1941, Serial No. 374,996

5 Claims. (01. 74-286) The power transmission mechanism of the presentinvention is designed to permit varia tions inspeed of powertransmission through out a wide range, and by the employment of aself-contained group of mechanisms which may be easily and accuratelyapplied to mechanism or equipment requiring variation in speed ofoperation. e

The device of the present invention has been designed primarily for usein the driving of the feed mechanism employed in the feeding of sheetsof sensitized paper through a photo-printing machine in which a widerange in the period of exposure is desirable, although the variablespeed mechanism is equally adapted for use in connection with othertypes of machines or appliances.

Further objects and details will appear from the description of theinvention in conjunctionline 4-4 of Figure 1, looking in the direction.

of the arrows i 9 Fig. 5 is-aTongitudinal sectional detail of variablespeed drive pulley;

Fig. 6 is a sectional view taken on line 6-6 of Fig. 2, looking in thedirection of the arrows; and

Fig. 7 is a-sectional view through the pivoted motor platform with theadjusting connections in elevation.

The variable speed assembly comprises a motor which is supported by thearms ll of a cradle i2 mounted upon a rectangular platform l3. The motorshaft l4 carries a pulley l5 over which runs a belt I6 wedge-shaped incross section. The beltis carried around a smooth faced pulley |1mounted upona primary worm shaft l8, and thencearound a groovedadjustable pulley I9 which comprises a fixed section keyed upon asecondary worm shaft 2|, and a movable section 22 provided with a hub 23which is slidably mounted upon the hub 24 of the fixed pulley section.The movable section is backed by a spring25 which is housed within anannular recess 26 and bears against a cap 21 on the end of the hub ofthe fixed pulley section.

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The fixed and movable pulley sections have oppositely disposed beveledfaces, which are reciprocally notched as at 28 to afiord an interlockingfit-with one another, which maintains the interlocking relation despitevariations in the spread between the pulley sections,occasioncd by thedrawing in of the wedge-shaped belt l6, which may be positioned as shownin full lines in Fig. 5, or drawn inwardly into comparatively closerelation to the interfitting hubs of the fixed and movable pulleysections, or adjusted to po- I sitions more nearly adjacent to theperiphery of the divided pulley. A pulley'of this character is standardand no claim is made for this device per se.

The primary and secondary worm shafts l8 and 2| are joumalled throughthe side walls of the casing 29 which houses the difierential mechanismnow to be described. I f The primary worm shaft l8 carries a worm 30,and the secondary worm shaft 2| carries a worm 3|. The worm 30 mesheswith a ring-shaped gear 32 which is mounted upon the face of theshouldered hub 33 of the cage 34. The hub is keyed to the shaft 31, andon the other side mesh with a transmission beveled pinion 45 the hub ofwhich is journalled upon inner ball bearings 46 and outer ball bearings41 carried by the reduced end of the shaft 31 which is journalled at itsterminus within ball bearings 48 mounted within a boss 49 in the endwall 50 of the casing and held in place by a cap 5|. The adjacentportion of the cage is mounted upon ball bearings 52 which are carriedby the hub of the transmission pinion 45, which also has keyed thereon ahub 53. of a transmission worm gear 54 meshing with the worm 3|.

The arrangement is such that the cage with the revolving pinions will bedriven at a constant speed through the fiat faced pulley l1, primaryworm shaft l8, Worm 30 and worm gear 32, and in the absence ofresistance the teeth of speed and direction of rotation imparted to thedriven shaft, therefore, will depend upon the speed of rotation impartedto the transmission pinion 45 through the variable speed drive affordedby the divided grooved pulley.

Thus, with the transmission pinion 45 rotating in the same direction asthe rotation of the cage carrying the revolving pinions, and at a rateof peripheral speed equal to the peripheral speed of the revolvingpinions, the latter will be per mitted to rotate freely around theirrespective shaftsduring their orbital travel upon the face of the drivenpinion 44, so that no resistance will be afforded to impart rotation tothe driven shaft 31, which in these conditions will stand stationary.

If, however, the speed of rotation of the pinion 45, in the samedirection as the cage, exceeds the speed of rotation imparted to therevolving orbital pinions by-the rotation of the cage, a thrust will beestablished which imparts an opposite rotation to the driven shaft 31.In like manner, when the speed of rotation of the transmission pinion 45is less than the neutral rotation of the orbital pinions, the samedirection of rotation will be imparted to the shaft 31.

As shown in Fig. 5, the belt it occupies an intermediate position withinthe divided pulley, which represents the neutral or idle conditionwithin which the rotation imparted to the transmission pinion 45 isequal and in the same direction as the rotation of the orbital pinionsimparted by the cage. By drawing in the belt I6 toward the axis of theshaft 2|, the speed of rotation'of the pinion 45 is rapidly increased,with resultant opposite rotation of the driven shaft,

so that in practical operation it is easily possible by the selection ofappropriate gears 'to 1m.- part to the driven shaft variations in speedof unlimited ratio, and also by allowing the belt [6 to move outwardlybeyond the intermediate position it is possible to provide variablerotation of the driven shaft in the same direction as the pinion 45.

In order to adjust the position of the belt It, the motor platform isis-hingedly mounted upon a pivot rod 55 entered through a suitablehanger bracket 56 forming part of the frame of the machine, which asshown depends from a platform 51 which supports the variabletransmission casing. For quick changing of speed the free edge of theplatform I3 is tilted upwardly by means of a thrust connection 58operated by a foot treadle 59.

For a selected normal operating speed the parts are positioned throughthe medium of an adjusting screw 60 entered through a screw block 6|mounted between trunnions 62 in a bracket 63 pivotally secured forupward lifting under the edge of the platform [3, which permits theplatform to be raised independently of the thrust connection operated bythe foot treadle while allowing the foot treadle to thrust the platformupwardly regardless of its selectively adjusted position. The adjustingscrew is provided at its upper end with a beveled pinion 64 meshing witha beveled pinion 65 on a shaft 66 rotated by a sprocket chain 61actuated by a hand wheel 68.

In order to arrest the movement of the platform [3 at zero speed, aplunger 69 is provided, backed by a spring located within a tubularsleeve 1| and adjustable by the provision of nuts 12, so that when theplatform strikes the end of the plunger, an indication is given to theoperator that the neutral or zero adjustment has been reached.

As the belt is drawn inwardly toward the axis of the shaft 2|, thespring tension against the sides of the belt increases, and, to balanceagainst 4 increase intension, a compensator, shown in Fig.

2, is provided, which consists of a sprocket chain 13, one end of whichis secured to the free edge of the platform l3, and thence carriedaround an eccentrically mounted sprocket wheel 14 and secured to aspring 15 connected with a fixed portion of the frame.

The sprocket wheel I4 is eccentrically mounted in such relation that asthe platform I: is drawn downwardly and the belt I6 is drawn inwardly,and as increasingspring pressure is imposed upon the movable member ofthe divided pulley, the

pull of the spring I5 will be imparted through an increased lever ratioto balance against the tendency of the divided pulley to force thebeltoutwardly toward the periphery. Thus, these forces tend to balanceagainst one another and permit even and accurate adjustment of theplatform II to hold the belt in properly adjusted position to secure thedesired variable speed ratio.

In Fig. 4 we have indicated the various positions of adjustment of themotor shaft to secure the various speed ratios within the range of themechanism shown. With the platform adjusted to bring the motor shaft tothe center indicated by the legend High speed, the driving belt will bedrawn in to a point closely adjacent to the hub 24 of the fixed pulleysection, while intermediate adjustments up to the center marked Neutral,will afford the desired variations of:

' 16 and a sprocket chain 11 to the sheet or web feeding mechanism of aphoto-printing machine. but it is not deemed necessary to describe suchmechanism, which serves merely for Purposes of illustrating one of thenumerous uses to which the present invention may be applied.

The arrangement is one in which a comparatively slight variation in thespeed of rotation of the driving pinion 45, with relation to therotation of the cage 34 and the orbital moving pinions, may be utilizedthrough suitable gear ratios to multiply the variation in speed impartedto the driven shaft 31, and in view of the fact that the employment of adivided pulley permits of an infinite number of intermediateadjustments, it is thus possible to provide for a wide range andaccurate variation at any speed ratio desired.

For ordinary service, the employment of a foot treadle will suflice togive the desired speed variations, but where greater accuracy isdesired, the screw adjustment may be employed in lieu of the foottreadle, it.being understood that where the foot treadle is to beemployed solely, the adjusting screw may be disconnected.

Although the invention has been described with particularity as todetail, it is not the intention, unless otherwise indicated in theclaims, to limit the invention to the mechanism shown,

since modifications in detail may be made without departing from theprinciple of the invention.

We claim:

1. In variable speed transmission mechanism, the combination of aprimary shaft and a secondary shaft each-provided with a worm, a wormgear meshing with the primary worm and a cage carried by said worm gear,orbital gears rotatably mounted within the cage and revolving there-'with, a driven shaft in train with said orbital gears, transmission gearmeans in train with. the secondary worm and with the orbital gears,means for imparting variable speeds of rotation to the secondary shaftand the gear means in train therewith, said means including a dividedpulley and a belt adapted to be variably adjusted with relation to theaxis of the pulley, a pulley on the primary shaft over which said belttravels to impart uniform rotation thereto, a motor having a constantlydriven pulley with whichsaid belt is engaged, and an adjustable mountingfor the motor to vary the position of the belt with relation to the axisof the divided pulley.

2. In variable speed transmission mechanism, the combination of aprimary shaft and a secondary shaft each provided with a worm, a wormgear meshing with the primary worm and a cage carried by said worm gear,orbital gears rotatably mounted within the cage and revolving therewith,a driven shaft in train with said orbital gears, transmission gear meansin train with the secondary worm and with the orbital gears, means forimparting variable speeds of rotation to the secondary shaft and thegear means in train therewith, said means including a divided pulley anda belt adapted to be variably adjusted with relation to the axis of thepulley, a pulley on the primary shaft over which said belt travels toimpart uniform rotation thereto, a motor having a constantly drivenpulley with which said belt is engaged, a hinged platform upon which themotor is mounted, and means for varying the position of the platform andmotor to adjust the belt with relation to the axis of the dividedpulley.

3. In variable speed transmission mechanism, the combination of aprimary shaft and a secondary shaft in spaced parallel relation to oneanother and each provided with a driving gear member, a driven gearmember meshing with the primary driving gear member and a cage carriedby said driven gear member, orbital gears rotatably mounted within thecage and revolving therewith, a driven shaft in train with said orbitalgears, transmission gear means in train with:

the secondary gear member and with the orbital gears, means forimparting variable speeds of rotation to the secondary shaft and thegear means in train therewith, said means including a divided pulleyhaving a spring backed member and a belt adapted to be variably adjustedunder tension with relation to the axis of the pulley, a pulley on theprimary shaft over which said belt travels to impart uniform rotationthereto, a motor driving a constantly rotating pulley with which saidbelt is engaged, an adjustable mounting for the motor to vary theposition of the belt with relation to the axis of the divided pulley,screw means for accurately adjusting the position of said mounting, andtreadle means engaging said mounting for imparting quick ad- Justmentsthereto independently of the screw adjustment.

4. In variable speed transmission mechanism, the combination of aprimary shaft and a secondary shaft in spaced parallel relation to oneanother and each provided with a driving gear member, a driven gearmember meshing with the primary driving gear member and a cage carriedby said driven gear member, orbital gears rotatably mounted within thecage and revolving therewith, a driven shaft in train with said orbitalgears, transmission gear means in train with the secondary gear memberand with the orbital gears, means for imparting variable speeds ofrotation to the secondary shaft and the gear means in train therewith,said means including a divided pulley having a spring backed member anda belt adapted to be variably adjusted under tension with relation tothe axis of the pulley. a pulley on the primary shaft over which'saidbelt travels to impart uniform rotation thereto,

a motor .driving a constantly rotating pulley with which said belt isengaged, a hinged platform upon which the motor is mounted, screw meansconnected with the platform for accurately varying the position of theplatform and motor to adjust the belt with relation to the axis of thedivided pulley, and treadle means engaging the platform for impartingquick adjustments thereto independently of the screw adjustment.

5. In variable speed transmission mechanism, the combination of aprimary shaft anda. secondary shaft in spaced parallel relation to oneanother and each provided with a driving gear member, a driven gearmember meshing" with the primary driving gear member and a' cage carriedby said driven gear member, orbital gears rotatably mounted within thecage and revolving therewith, a driven shaft in, train with said orbitalgears, transmission gear means in train with the secondary gear memberand with the orbital gears, means for imparting variable speeds ofrotation to the secondaryshaft and the gear means in train therewith,said means including a divided pulley having a spring backed member anda belt adapted to be variably adjusted under tension with relation tothe axis of the pulley, a

pulley on the primary shaft over which said belt travels to impartuniform rotation thereto, a motor driving a constantly rotating pulleywith which said belt is engaged, a hinged platform upon which the motoris mounted,'a pivoted bracket projecting outwardly from theplatformf andadapted to impart lifting movements thereto,.

to the platform, and treadle means positioned to impart a lifting thrustto the pivoted platform independently of the screw adjustment.

PAUL B. STREICH. HERBERT G. MACDONALD.

